The proposed work includes: 1. Skin testing additional subjects to establish possible correlations between severity of periodontal disease and immediate and delayed hypersensitivity to Actinomyces viscosus, Bacterionema matruchotii, Bacteroides melaninogenicus and Fusobacterium nucleatum. 2. Study further the in vitro histamine assay for immediate hypersensitivity. Leukocytes from patients will not only be challenged with sonicates of A. viscosus but also with sonicates of other microorganisms outlined in 1 above. Increased numbers of patients with known severity of periodontal disease will also be tested. 3. Sera from the acute and convalescent phase of ANUG will be studied for titers to oral spirochetes. Debris from additional patients with ANUG will be studied for in vivo coating with immunoglobulins and complement. 4. Biopsies and sera from additional patients with desquamative gingivitis will be studied for autoantibodies. BIBLIOGRAPHIC REFERENCES: Nisengard, R. J., et al.: Diagnostic importance of immunofluorescence in oral bullous diseases and lupus erythematosus. OOO 40: 365, 1975. Nisengard, R. J. and Jarrett, C.: Coating of subgingival bacteria with immunoglobulin and complement. IADR Abstract, J. Dent. Res. 54:122, 1975.